liquid. The waste in cork-making amounts to about sixty per cent; but the chips can all be put to profitable use in making chalk-powders, linoleum, and feltings.
A large number of other substitutes for stoppers of cork have been tried. Those which have given the most satisfaction, in particular cases, are made of ground-glass and India-rubber; but no other device has come into a real competition with cork.
Fig. 3.—Machine for Trimming Corks.
Mr. William Anderson, describing some new applications of the mechanical properties of cork to the arts, insists, as the peculiar quality which distinguishes it from all other solid or liquid bodies, upon its power of altering its volume in a very marked degree m consequence of change of pressure. All liquids and solids are capable of cubical compression or extension, but to a very small extent; thus water is reduced in volume by only 1/2000 part by the pressure of an atmosphere. Liquid carbonic acid yields to pressure much more than any other fluid, but still the rate is very small. Solid substances, with the exception of cork, offer equally obstinate resistance to change of bulk, even India-rubber, which most people would suppose capable of very considerable change of volume, being really very
